This invention relates to nonwoven mats suitable for use as battery separators and, more particularly, to such mats with surfactants included in their fibers.
It has in the past been recognized that the provision of permanent wetting characteristics was important to good battery separator performance as indicated by U.S. Pat. No. 3,154,436. Special emphasis has been given to the problem because of the practice of providing dry charge batteries. In producing dry charge batteries a particularly severe problem is caused by the formation of the battery, i.e. the initial charging of the battery. After charging, the battery assembly must be washed to remove the acid. This washing, of course, tends to remove any wetting agent present in the separator. After washing it is the usual practice to heat dry the battery assembly and thus any wetting agent that is to be retained must have resistance to decomposition or volatilization under such circumstances. The long term bathing and agitation of the separators in a battery during use, in for example, an automobile also presents extreme conditions testing wetting agent retention. A battery separator is also subjected to surface abraiding against the battery plates and scouring by bubbles.
Other patents indicating battery environment difficulties with wetting agents include U.S. Pat. Nos. 2,773,114; 2,707,201; 2,662,032 and 2,662,107. U.S. Pat. No. 2,482,062 shows wetting agents used in fibrous battery separators.